Process of refining animal and vegetable oils



Feb. 13, 1940. I CLAYTON 2,190,593

PROCESS OF REFINING ANIMAL AND VEGETABLE OILS Filed March 3, 1939 Milk/775$ VACUUM swam M Patented Feb. 13, 1940 PROCESS OF REFININGANMAL- AND VEGETABLE OILS Benjamin Clayton,

Nevada Houston, Tex, assignmto Refining, Inc., Reno, New,

a. corporation or Application March a, 1939, Serial No. 259,502

28 Claims.

This invention relates to the refining of animal and vegetable oils, and more particularly to a process in which a mixture formed by adding a neutralizing agent to the oil is dehydrated prior to separation.

In the refining of vegetable and animal oils, it is conventional to add an aqueous caustic soda solution to the oil to neutralize the free fatty acids contained therein. The caustic soda reacts with the fatty acids to form soap. An excess of caustic soda is employed during the neutralization step both to render the soap stock more easily separable and to reduce the color of highly colored oils. This excess also saponifies large amounts of neutral oil to form soap and glycerine. Most oils also contain substantial proportions of gums such as phosphatides, proteins, resins, etc. The neutralizing agent also precipitates these gums. The resulting soap stock, which may include water, soap, gums, glycerine, coloring matter, and excess caustic soda, is then separated from the refined oil by ,a single centrifugal separation or gravity settling. Thecharacter of the soap stock is such that large amounts of neutral oil are entrained in the soap stock. The amount of neutral oil lost in the process both by saponification of neutral oil and entrainment of oil in the soap stock constitutes a substantial portion of the oil being refined. The dehydration and rehydration steps of the present invention, however, appear to modify such soap stock so that very little oil is entrained therein, particularly when centrifugally separated.

Many alkaline reagents will neutralize the free fatty acids and precipitate the gums without saponifying neutral oil. The employment of such non-saponifying alkalies, however, produces soap stock which is more difficultly separable from the oil than soap stock from caustic refining. Also, in the case of highly colored oils, the non-saponifying alkali doesnot sufiicientlyreduce the color of the oil. The dehydration treatment of themixture resulting from adding a non-saponiiying neutralizing agent in accordance with the present invention enables the soap stock to be cleanly separated from the oil without substantial entrainment of neutral oil. Furthermore, the present invention contemplates treating the oil with a color reducing agent, in the case of highly colored oils, in order to produce a commercially acceptable oil. The color reducing agent may be added prior to separation of the soap stock. However, the color reducing agent found most effective is a caustic alkali which will attack neutral oil and, by treating the oil with such a color resoap stock produced in the neutralization step,

the color impurities, along with excess color reducing agent, can be separated from the oil as a thin liquid containing substantially no entrained oil. Thus, by employing distinct neutralizing and color reducing steps, the temperature and other conditions most favorable to these steps can be used, such that refining losses are minimized.

One of the major advantages of the present invention is,that the employment of dehydration and rehydration and also of distinct steps for neutralization and color reduction, enables temperatures, time of treatment and concentration and amount of agents in the various steps to be varied independently to fit the particular oil being treated so that the various types of vegetable and animal oils encountered may be refined without major changes in the apparatus ployed.

It is, therefore, an object of the present invention to provide a process of refining animal and vegetable oils in which refining losses are materially less than in prior processes.

Another object of the invention is to provide a process in which the mixture of oil and soap stock formed by adding a neutralizing agent to the oil is subjected to dehydration to remove water and volatile impurities from the oil and is then rehydrated prior to separation by difference in specific gravity in order to reduce the amount of oil entrained in the soap stock.

Another object of the invention is to provide a process in which a refining reagent which will not attack neutral oil is employed in the neutralizing step in order to reduce the refining losses.

Another object of the invention is to employ a .non-saponifying alkali as the neutralizing reagent, and thereafter treat the oil with a color reducing agent.

Another object of the invention is to provide a process employing a non-saponifying alkali as a neutralizing agent in which the soap stock resulting from neutralization is separated from the oil and the oil thereafter treated with a color reducing agent.

A further object of the invention is to provide a process in which neutralization and color reductiorf are carried on as separate steps under different temperature conditions and times of treatment so as to produce a high quality oil with minimum refining losses.

A still further object of the invention is to provide a process of refining vegetable and animal oils which is adaptable to the various types of oils encountered.

Other objects and advantages of the invention will appear in the following description of preferred embodiments thereof, given in connection with the attached drawing, of which:

Figure 1 is a schematic diagram of an apparatus capable of carrying out a complete refining operation; and

Figure 2 is a similar view of an alternative form of mixing the oil and neutralizing agent.

Referring more particularly to Figure 1: l and H indicate mixing receptacles for the oil and neutralizing agent. Oil to be refined may be introduced into the receptacles l0 and il through pipes l2 and I3, while neutralizing agent may be introduced into these receptacles through a pipe l4. The receptacles l0 and H are preferably provided with an agitator l5 driven from any suitable source of power through pulleys or sprockets IS. The receptacles are also preferably provided with a means for heating the contents thereof which may be heating coils I! through which any desired heating medium such I as steam may be passed. The mixing receptacles l0 and II are intended to be used alternatively so that a mixture may be prepared in one receptacle while being withdrawn from the other receptacle for subsequent treatment in the process, although a single kettle can be employed.

In the preferred process, a non-saponifying alkali is employed, in which case the receptacles may be, if desired, of large size such as the conventional batch refining kettles of the prior art holding up to as much as 60,000 pounds of ofl. The mixing receptacles, however, may be, and preferably are, of smaller size, or the number of centrifugal separators may be increased so that the mixture is not subjected to agitation for extremely long periods of time.

The mixture prepared in the receptacles ill and I I may be'withdrawn therefrom by means of a pump l8 through pipes l9 and 20, respectively, by suitably adjusting the valves in the pipes l9 and 20. The pump l8 preferably delivers the mixture through a heating device 2| which may include a coil 22 positioned in a casing 23 through which any desired heating means may be circulated. The mixture is passed through the coil 22 and then delivered into a dehydrating chamber 24.

The dehydrating chamber 24 is preferably maintained under relatively high vacuum by withdrawing water and other vapor from the chamber through a pipe 25 into a condenser 28 provided with a receiver 2'!.to which a vacuum pump 28 is connected in order to maintain the vacuum in the receiver 21, condenser 26 and dehydrating chamber 24. The dehydrating chamher is also preferably provided with an agitator 29 driven by a motor 30 and with a heating means which may be a heating coil 3! through which any desired heating medium such as steam may be passed. The agitation in the dehydrating chamber not only assists in vapor removal but prevents any stratification of the soap stock, and oil, so that a substantially uniform mixture of oil and soap stock is maintained therein and discharged therefrom. The mixture from the coil 22 is preferably maintained in the dehydrating chamber for sufficient time and at sufficient temperature to cause substantially all of the water to be withdrawn from the mixture in vapor form along with other vaporizable materials. If desired, vapor separation may be assisted by delivering superheated steam into the lower portion of the mixture through a steam distributor 33. The introduction of the steam also agitates the mixture so that the mechanical agitator 23 may sometimes be omitted if introduction of steam is employed.

The mixture of oil and substantially dehydrated soap stock is withdrawn from the dehydrating chamber by means of a pump 34. As the dehy-- drated soap stock can not be efliciently separated from the oil by ordinary centrifugal or gravity separation, it is necessary to rehydrate the mixture in order to centrifugally separate the same and in order to reduce the color of certain oils. This may be accomplished by withdrawing a hehydration agent from a tank 35 by means of a pump 36 and delivering the same into a flow mixer 31 to which the mixture from the dehydration chamber 24 is also delivered. As the temperature of the oil withdrawn from the dehydrating chamber 24 is not ordinarily the temperature found necessary for most effective separation of the particular from the mixer 31 is preferably passed through a heat exchange device 38. The heat exchange device may include a coil 39 through which the mixture is passed and which coil is positioned in a casing 40 through which a desired heating or cooling medium may be circulated. Even if no change in temperature is desired, the heat exchange device 38 is an effective means for providing a time of treatment of the mixture with the rehydrating agent.

In many cases, it has also been found that separation is improved by introducing additional rehydrating agent into the mixture just before separation of the soap stock from the oil contained therein. This may be accomplished by withdrawing the additional rehydrating agent from a tank 4| by a pump 42 and delivering the same into a flow mixer 43 into which the mixture from the coil 39 is introduced. The resulting mixture is then preferably separated by centrifugal force in a plurality of centrifugal separators 44 operating in parallel. The rehydrating agent may, in some instances, be heated water, but in general will be solutions of salts which promote separation and have no deleterious eefict upon the oil. With-certain oils it has been found that best results are obtained by introducing rehydrating agent prior to passing the mixture through the heat exchanger 38, while with other oils the rehydrating aration if introduced just before the mixture enters the centrifugal separators 44. In such case the mixer 31 may be eliminated or bypassed. Also, if no change in temperature between the dehydrating chamber 24 and the centrifugal separator 44 is found desirable, the heat exchanger 38 may also be eliminated or bypassed or employed to give a time interval for rehydration by the rehydration agent. For this purpose it is also possible to employ a tank in which the mixture of oil, soap stock and rehydrating agent is held for a short period of time under agitation oil being treated, the mixture agent provides better seplust troducing the rehydrating agent into the mixture a short time prior to separation, while with other oils the agent should be introduced into the mixture just before it enters the separation zone or even within the separator itself so as to function as a flushing agent contacting substantially only the soap stock, for example, into a centrifugal of the general type disclosed in the application of Benjamin H. Thurman, Serial No.

250,428, filed January 11, 1929.

With some oils it is found advantageous to deliver both rehydrating agent into the mixer 31 and additional rehydrating agent into-the mixer 43 or into the centrifugal separator in order to secure most eflicient separation. In most cases both rehydrating agents will be solutions of the same salt such as solutions of sodium sulfate, sodium carbonate or ammonium sulfate,but may 4 be solutions of different salts or mixtures of salts and have different concentrations. Both the rehydrating agents may be introduced into the mixers 31 and 43 at the same temperature as the oil and soap stock mixture entering the mixers or they may be employed to increase or decrease the temperature of the final mixture. In order to adjust the temperature of the rehydrating agents to the desired point. heat exchange coils and 46 through which any desired heating or cooling medium may be passed are preferably positioned in the tanks 35 and 4i respectively. The streams of rehydrating agents are preferably accurately proportioned with respect to the stream of mixture. One way of accomplishing this is to drive the pumps 34, 36 and 42 by a variable speed motor 45' with variable speed devices 46' positioned between the motor and pumps 34 and 42.

The resulting mixture is separated in the centrifugal separators 44. The soap stock and rehydrating agents constitute the heavier effluent and are discharged from the centrifugals through spouts 41 into receivers 48. The neutralized oil is discharged from the centrifugal separators as the light efiluent through pipes 49 into a receiver 50. When oil is originally of low color and its color has not been sufficiently reduced in the rehydration and separation step, neutralized oil is withdrawn from the receiver 50 by means of a pump 5| and delivered through a heat exchange device 52 to a flow mixer 53. Color reducing agent, which is ordinarily a solution of caustic soda, is withdrawn from the tank 54 and delivered by a pump 55 to the mixer 53. The pumps 5| and 55 may be driven by a variable speed motor 56 with a variable speed device 51 positioned between the pumps so that the oil and color reducing agent may be accurately proportioned. Any other proportioning mechanism capable of delivering accurately proportioned streams of oil and color reducing agent may, however, be employed. The heat exchange device 52 is employed to bring the oil to the desired temperature of mixing, which is usually less than the temperature of the oil in the tank 50, and a heat exchange coil 58 is preferably positioned in the tank 54 in order to bring the color reducing agent to the desired tempera ture of mixing. The mixture from the mixer 53 is preferably through a heat exchange .device I in order to. give a desired time of treatment to the oil by the color reducing agent. This treatment is preferably at a relatively low tem-' perature, as the color reduction action appears to go forward at a greater rate at low temperatures and also lower temperature retards saponiflcation of neutral oilbythe color reducing agent.

The color reducing agent, along with color impurities, is: preferably centrifugally separated from the refined oil and, as the most effective temperature of separation is usually higher than that at which color reduction is most effective, the mixture from the heat exchanger 59 is preferably passed through another heat exchange device 60 in which the temperature of the mixture is rapidly raised to that desired for centrifugal separation. After having been passed through the heat exchanger 30, the mixture is preferably delivered to a plurality of centrifugal separators 6| operated in parallel. Any excess color reducin agent and the color impurities are discharged as the heavy eiiiuent through spouts 62 in the receiver 63, and the refined oil is discharged through pipes 64 into a receiver 65. In. general, the number of centrifugalseparators necessary for the color reduction step is less than the number required for the separating step, as the amount of heavy eiiluent is relatively very small.

The centrifugal separators 6i for separating the color impurities from the refined oil, as well as the centrifugal separators 44 for separating the soap stock from the neutralized oil, arepreferably of the heated type disclosed in Patent No. 2,100,277, granted November 23, 1937. Such heated centrifugals are particularly useful for separating the soap stock from the neutralized oil,

as they prevent sticking of the soap stock to the walls of the centrifugal bowl and, if suflicient heat is supplied thereto, they may also be employed to raise the temperature of the soap stock and oil during separation. Also, in separating the color.

impurities from the refined oil, the heated centrifugals may be employed for increasing the temperature of the materials being separated at a rapid rate, so that the amount of heat necessary to be imparted to the mixture in the heat 'exchanger 60 in order to provide effective separation may be minimized to thereby minimize the time during which the mixture is subjected to the temperature of separation.

In order to remove residual impurities from the refined oil and wash out color precipitated but not separated in the color reduction step, the refined oil may be withdrawn from the receiver 55 by means of a pump 66 and delivered through heat exchange device 61 to a flow mixer 68. Wash water may be withdrawn from a tank 69 by means of a pump 10 and delivered to the mixer 68. The pumps 66 and 10 are also preferably proportioning pumps and may be driven by a. variable speed motor 69' with a variable speed device 10' between the motor and one of the pumps. The washing operation is preferably carried on at a relatively high temperature and the heat exchanger 61 may be employed to bring the oil to the desired temperature. Also, the tank 68 may be provided with a heating coil II in order to heat the wash water to the desired temperature. The wash water is preferably separated from the oil shortly after being mixed therewith, and the mixture of oil and water may be delivered directly to a plurality of centrifugal separators I2 operated in parallel, although it is some imes advantageous to pass the mixture through a coil 12' in order to provide a treating time prior to separation. Water containingresidual impurities is discharged from the separators as the heavy emuent through spouts 13 into receiver 14 and the washed oil is discharged through pipes 15 into a receiver 18. As the washed oil usually contains a small amount of moisture, it is preferred to dry the oil before discharging the same from the process. This is most efllciently accomplished by vacuum drying the oil'in a vacuum chamber 11. A vacuum may be maintained in this chamber by connecting the same through a pipe 18 to the pipe leading to the condenser 26. The vacuum in the chamber 11 may be employed to withdraw the oil from the receiver 16 through heat exchanger 19 into the vacuum chamber 11. The heat exchanger 19 may be employed to increase the temperature of the oil so as to more easily cause the water to be liberated therefrom in vapor form. The vacuum chamber 11 may also be provided with a heating coil 80 or other heating device for supplying heat to the oil therein. In order to assist liberation of vapors from the oil, superheated steam may be passed through a body of oil in the vacuum chamber 11 by means of a distributor 8| positioned in the lower portion of the chamber. By subjecting the oil to relatively high temperatures in the presenceof superheated steam, the vacuum chamber 11 may be employed to'bleach and deodorize the oil as well as dry the same.-- The dried oil may be withdrawn from the chamber 11 by means of a pump 82 and deliveredto a storage tank 88.

In Figure 2 an alternative form 01. apparatus for mixing the oil and neutralizing agent is disclosed. In this figure the neutralizing agent may be continuously mixed with the oil 'by withdrawing a stream of oil from a storage tank 84 bygmeans of a pump 85 and delivering the same through a heat exchange device 88 to a. flow mixer 81. A stream of neutralizing agent may be withdrawn from the tank 88 by a pump 89 and delivered to the mixer 81. The pumps 85 and 89 may be driven by a variable speed electric motor 90 with a speed exchange device 92 positioned therebetween' so as to deliver accurately proportioned streams of oil and neutralizing agent to the mixer 81. Any other type of proportioning mechanism capable of delivering accurately proportioned streams of oil under pressure to the mixer 81 may, however, be employed.

The mixture from the mixer 81 may then be delivered to a heat exchanger 23 which may be the same as the heat exchanger 23 of Figure 1,

and may thereafter be carried through the subsequent steps of the process described with reference to Figure 1. The heat exchanger 88 is employed to bring the oil to a desired temperature of mixing, and the tank 88 may be provided with a heating oil 93 to adjust the temperature of the-neutralizing agent to the desired temperature of mixing. The temperature at which the oil and neutralizing agent is mixed will depend upon the nature of the oil being treated. With certain oils, mixing at low temperatures, for example room temperature, is found most emcient, while with other oils higher temperatures produce better results.

In the process of the present invention, the preferred neutralizing agent is sodium carbonate. As sodium carbonate does not attack neutral oil, it may be mixed with the oil in the receptacles l0 and II of Figure 1 and agitated until a thorough mixture is obtained. Other nonsaponifying neutralizing agents such as disodium hydrogen phosphate, trisodium phosphate, sodium silicate, their equivalent potassium salts, or other alkali metal salts of weak acids, may be employed. These non-saponifying' neutralizing agents 'have not heretofore been employed in commercial oil refining processes, as in prior processes the oil was not completely neutralized; also, the resulting soap stock could not be satisfactorily separated' from the oil by settling or centrifugal separation and, in the case of highly colored oils, the color was not sufliciently reduced. Sodium carbonate was particularly difiicult to employ, as carbon dioxide tended to form so as to interfere with separation of the soap stock, and an equilbirium was set up to prevent substantially complete neutralization of the on. Also, the soap stock produced by non-saponifying alkalies is, in

general, too light and finely divided for ,efilcient separation from the oil by difference in specific gravity. .It has been found that the dehydration treatment of the mixture in accordance with-the present invention removes any carbon. dioxide which tends to form and that substantially complete neutralization is eflected even-if amounts of sodium carbonate equivalent to the free fatty acids are employed. The dehydration of the mixture,.coupled with subsequent rehydration, furthermore appears to modify the nature of the soap stock and destroys the light finely divided condition originally encountered with non-saponifying alkalies. Improved gravity or centrifugal separation is even produced where conventional refining reagents such as caustic alkalies are employed as neutralizing agent. By employing the dehydration steps of the present invention to improve separation, such neutralizing reagents as alkaline earth metal hydroxides, for example, calcium hydroxide, barium hydroxide or magnesium hydroxide or their salts of weak acids may be employed as solutions or slurries. The soaps formed are more soluble in the oil than alkali metal soaps, but the rehydrating agent throws such soaps out of solution in the oil prior to separation. The various neutralizing agents mentioned may be employed singly or in various admixtures. It is sometimes advantageous to employ neutralizing agents which liberate hydrogen peroxide or free oxygen when mixed with water, as the oxygen is eflective to reduce the color and odor of the oil. Examples of such neutralizing agents are sodium peroxide or sodium perborate. Sodium peroxide also forms sodium hydroxide for neutralization, while sodium perborate forms sodium borate, which is a non-saponifying alkali. These oxygen liberating agents may be used alone or in admixture with each other or with any of the other neutralizing agents with which they are compatible. The oxygen is removed from the mixture in the dehydrating step so that continued contact between the oil and oxygen does not occur.

When non-saponifying alkalies are employed,-

the temperature of mixing may be merely that which will render the oil fluid or may be relatively high, as high temperatures do not cause saponification of neutral oil. Thus, temperatures from 70 F. and below up to 160 F. have been employed, although temperatures in the lower portion of this range are preferred. When the oil in one of the receptacles l0 and H has been brought to the desired mixing temperature, sufficient neutralizing agent usually in relatively concentrated aqueous solution is introduced into the oil and the agitator run at relatively high era], the greater the lies may be employed without attack upon the neutral oil. The concentration of the neutralizing agent is not critical, and may range between wide limits. As the water is to be subsequently removed, the more highly concentrated solutions are preferred. In many cases, it has been found possible to employ slurries of the neutralization agent containing more agent than will dissolve in the water and even relatively dry neutralization agents. Other liquids than water, for example, volatile alcohols and their esters or hydrocarbins can be employed to carry the neutralization agent, as such liquids are removed from the oil and soap stock mixture during dehydration and can be condensed and reused in the process. In order to secure neutralization of the free fatty acids, with soda ash, however, moisture should be present during the neutralization.

As soon as a thorough admixture has been obtained, the agitation is preferably slowed to that which will Just maintain themixture and prevent stratification of soap stock. While a stream of the mixture is being withdrawn from one of the receptacles, another mixture may be prepared in theother receptacle so that a continuous stream may be delivered to the subsequent steps of the process. The mixture is preferably passed through the heat exchange device 2l in order to raise its temperature so as to cause water and other vapors to be more easily liberated therefrom in the dehydration tank 24. This temperature will odinarily range between 140 and 230 F. Additional heat may also be imparted to the oil in the dehydrating chamber, either by the heating coil 3| or superheated steam from the distributor 33, or both. Thus, temperatures in the dehydrating chamber may range from 160 F. to 250 F., depending upon the oil being treated and the amount of water and other vaporizable impurities to be removed. A relatively high vacuum is preferably maintained in the chamber 24, for example 2'? to 30 inches of mercury. The mixture therein is preferably agitated by means of the agitator 29 or superheated steam from the distributor 33, or both, in order to assist in liberating vapors from the mixture and minimize Stratification of the soap in any body of oil that exists in the zone of dehydration. It is preferred, although not essential, to remove substantially all of the water or other liquid in the mixture, that is, to produce a mixture containing as low as 0.1% volatile liquid, as, in gendegree of dehydration the less the losses by entrainment in the separation step. Dehydration destroys any emulsion which may form and also appears to condition the mixture so that emulsions do not form even if the mixture is subsequently rehydrated.

The dehydrated mixture of oil and soap stock when withdrawn from the chamber 24 can not be satisfactorily separated either by ordinary centrifugal separation or a settling operation.

It is, however, preferred to rehydrate the soap stock and continuously contrifugally separate. In some operations it is found desirable to introduce a rehydrating agent into both the mixer 31 and into the mixer 43. The preferred rehydrating agent is an aqueous solution of sodium sulfate, as this rehydrating agent apparently softens the soap stock, making it more easily flowable from the centrifugal separators M. An aqueous solutionof sodium carbonate has also been found very effective, as this reagent also appears to soften the soap stock to almost as great an extent as the sodium sulfate. Other possible rehydrating agents are water alone or aqueous solutions of sodium bicarbonate, sodium lactate, sodium tartrate, sodium naphthenate, sodium citrate, sodium pyrophosphate, ammonium sulfate, ammonium chloride, calcium sulfate, magnesium sulfate, borax, disodium phosphate, trisodium phosphate, sodium thiosulfate or sodium thiocyanate, as well as equivalent potassium salts. Sodium chloride may also be employed, although usually not as efllciently as sodium sulfate or sodium carbonate, as the sodium chloride tends to somewhat harden or grain out the soap stock, tending to cause the same to be less flowable and to stratify in the centrifugal separator. In general, alkaline metal or alkaline earth metal salts, as well as ammonium salts, which have no deleterious effect upon the oil may be employed individually or in various admixtures as well as water alone. Also, aqueous solutions or such materials as sugar and dextrose may be employed. Solutions which are at least slightly alkaline appear to give better results and solutions of salts which are normally not alkaline may be rendered alkaline by incorporating small amounts of alkalies such as caustic soda or sodium carbonate therein. The exact rehydrating agent employed as well as the concentration of the solution will depend upon the type of oil being refined. The soap stock re sulting from neutralization varies widely with different types of oil and is affected differently by the different rehydrating agents. In the majority of cases, however, sodium sulfate or sodium carbonate produce the best results and may be employed in concentrations-of from 1 to 30 B., again depending upon the type of oil being treated. Although the soap contained in the soap stock is usually somewhat more solube in the oil when dehydrated, the rehydrating agent throws any dissolved soap substantially completely out of solution in the oil.

The temperature of the oil coming from the dehydrating chamber 24 may be somewhat higher than that found most effective for centrifugal separation. The heat exchange device 38 is employed for reducing this temperature when necessary. The heating coil 45 in the tank 35 for the rehydrating agent is employed to bring the temperature of the rehydrating agent to a definite temperature. This is usually somewhat lower than the temperature of the oil withdrawn from the dehydrating chamber 24 in order to assist in cooling the oil. Thus, temperatures from 70 F. or lowerup to substantially the boiling point of water may be employed for the rehydrating agent. The additional rehydrating agent may comprise an aqueous solution of any of the salts or mixtures of salts described with respect to the first rehydrating agent and is employed to increase the amount of liquid material separated as heavy effluent from the centrifugal separators 44 so as to render this material more liquid and add weight to. the heavier efiluent. As in the case of the first rehydrating agent, the additional rehydrating agent preferably comprises an aqueous solution of sodium sulfate or sodium carbonate and, depending upon the type of oil being treated, the concentration of such solution may range from 1 to 30 B. The rehydrating agents render the soap stock flowable and weight the same so that it discharges smoothly and uniformly from the separators. They also prevent stratification of the soap stock in the centrifugal bowl. With some oil's, particular-1y degummed oil, the soap stock tends to remain in the bowl until it separates into two layers, a lighter one consisting primarily of soap, and a heavier one of residual gums and water. The soap layer then tends to discharge with the oil. By employing suflicient hydrating and flushing agent to cause the soap stock to discharge promptly, this stratification isiprevented.

In general, the total amount of rehydrating agents will not exceed 10%, but with certain oils may run as high as 20%. The temperature of the additional rehydrating agent will ordinarily be approximately that desired for centrifugal separation and the heating coil 46 positioned in the tank 4| is employed to bring the flushing agent to the desired temperature. The temperature of separation will vary with different oils being treated but will ordinarily be between 100 and 250 F. In general, the higher the temperature the better the separation until the temperature of priming is reached, as both the oil and soap stockare reduced in viscosity. One cause. of priming is gas or vapor liberation in the centrifugal separator and such priming results in a failure of separation. The dehydrating-treatment of the mixture removes gases and vaporizable material which may cause priming, and the employment of relatively highly concentrated solutions as rehydrating agents increase the boiling point of the heavier eflluent so that vapors are not formed at temperatures even above the boiling point of water.

In the preferred process the color reducing agent is mixed with the oil at a relatively low temperature. The heat exchange device 52 may be employed to bring the oil to the desired lower temperature, which temperature will ordinarily be below 100 F. and is usually just sufficient to maintain the oil in fiowable condition. Thus temperatures from or F. up to F. are contemplated. The heating coil 58 in the tank 54 for the color reducing agent may be employed to bring the color reducing agent to the desired mixing temperature. The color reducing agent is ordinarily a caustic alkali such as caustic soda. As the free fatty acids have already been substantially neutralized, a relatively small amount of color reducing agent is necessary. However, the amount and concentration of such agent will also vary with the oil being treated and the amount of color contained therein. Thus, for low colored oils no color reducing agent may be necessary, in which case the entire color reducing step may be eliminated. For highly colored oils such as cottonseed oil, 1 to 2% of a 12 B. lye solution is usually found sufficient. The concentration of the color reducing agent may be as high as 30 B. and will seldom be below 6 B., and from to 4% of solution may be employed, the more-concentrated and greater amounts of color reducing agent being employed for the more highly colored oils.

As color reduction increases with time of treatment with certain oils, it is preferable with such oils to run the mixture of oil and color reducing agent through a coil such as that contained in tive for centrifugal separation. In general, this temperature will be higher than the mixing and treating temperature in the mixer 53 and heat exchange device 59 and will usually range between 100 F. and 160 F. A part or all of this temperature may be imparted to the mixture in the heat exchange device 60 or, if the centrifugal separators 6| are of the heated type previously referred to, a part or all of the necessary temperature may be imparted to the mixture within the centrifugal separators. Thus, even such oils as cold pressed cottonseed oils or mixtures of cold and hot pressed oils and other oils which are diflicult to reduce in color may be treated with color reducing agents in suflicient concentration and amount and for sufiicient time at the proper temperature for effective color-reduction without substantial saponification or other loss of neutral oil.

The refined oil may then be washed'by injecting wash water into a flowing stream of oil in the mixer 68. If the wash water is'at relatively low temperature, the temperature of the oil may be increased in the heat exchange device 61 so that the desired temperature of separation in the centrifugal separator 12 may be secured. However, the water may be heated in the tank 69 by the heating coil 1| sothat the heat exchange device 61'may "be eliminated or employed to somewhat reduce the temperature of the oil in the tank 65. The temperature of separation in the centrifugals 12 is ordinarily quite high and will usually range between and 200 F. The amount of water admixed with the oil will again depend upon the nature of the oil being treated and may range between 5 and 30%, usually being about 15%. If it is merely desired to vacuum dry the oil without subjecting the same to drastic treatment for deodorization and bleaching, temperatures in the vacuum chamber I1 will usually range between and 200 F., although this temperature may be increased to 250 to 350 F. and the-oil treated .with superheated steam in order to 'deodorize and then the heat exchange device 2| employed to impart additional heat to the oil or to merely serve as a device for extending the treating time prior to introduction of the oil into the dehydrating chamber in case preheating temperatures in the upper portion of the range mentioned are employed. The temperature reached in the preheater 86 will depend upon the type of oil being treated, as some oils respond better to high preheating temperatures and others to heating the mixture in the heat exchange device 2|.

As stated above, the dehydration of the soap stock and subsequent rehydrationthereof appears to modify the soap stock to render it more easily separable. Thus, non-saponifying alkalies which ordinarily produce difiiculty separable soap stock can be employed in a refining operation and still produce low entrainment of neutral oil in the soap stock. However, this modification of the soap stock torender it more easily separable occurs even when saponifying neutralizing agents such as the conventional caustic soda are employed as a neutralizing agent. In such case the amount of oil entrained in the soap stock'is reduced. The continuous mixing step of Figure 2 is preferably employed when such caustic refining agents are employed in order to cut down the time of contact between the neutralizing agent and the oil and reduce saponiflcation of neutral oil. If a substantial excess of saponifying neutralizing agent is employed, the neutralizing agent also functions as a color reducing agent and the color reducing steps of the process can be eliminated. However, if the saponifying neutralizing agent is employed in amounts substantially equivalent to the free fatty acids in the mixing tanks l and II, no substantial attack on the neutral oil is produced even if the neutralizing agent is maintained in contact with the oil for extended periods of time and the batch mixing step of Figure 1 can be employed. The soap stock produced is, however, relatively easily beaten back into the oil so that care must be taken to maintain the agitation as low as possible to prevent stratification of the mixture in the receptacles l0 and II.

For highly colored oils, a color reducing step in which a color reducing agent is mixed with the oil after separating the soap stock therefrom is usually desirable. It is sometimes possible, however, to admix a color reducing agent such as an aqueous solution of caustic alkali with the mixture of oil and soap stock before it enters the centrifugal separators. The color reducing agent may then function as a rehydrating or flushing agent and may replace all or a portion of such rehydrating or flushing agents and may be added separately or in admixture with the rehydrating or flushing agent. It is sometimes possible to add a small amount of a color reducing agent with the non-saponifying neutralizing agent, particularly if a continuous mixing step is employed. In .such cases, and also in case the oil is originally of low color, the mixing apparatus for the color reducing agent may be eliminated, along with the centrifugal separators 6| for the color impurities. Other color reducing steps may sometimes be substituted for the treatment with caustic alkalies. For example, the addition of fullers earth, acid treated clay or other solid adsorbent followed by filtering or centrifugal separation to remove the adsorbent and color impurities may be employed. With certain oils, particularly those originally having a small gum content or those which have been degummed, the color may be sufficiently removed by a similar adsorbent treatment prior to neutralization, so that color reduction subsequent to neutralization with non-saponifying alkalies, may be omitted.

The washing of the refined oil with water and the subsequent drying has been found to be an extremely effective step of removing residual impurities from the refined oil, although other steps such as treatment with a filter aid such as fullers earth or acid treated clay and filtering may be substituted in lieu thereof. The water washing, however, appears to effectively reduce the color of the oil even though the oil delivered into the receiver 65 from the color reducing step is still quite highly colored. It further appears that the color reducing step described liberates or precipitates color impurities which are removed in the water washing step, even though not completely removed in the'color reducing step.

- Although continuous centrifugal separation steps have been specifically disclosed, the dehydration of' the oil and soap stock mixture prior to separation modifies the soap stock such that batch settling separation steps are also more effective than prior settling steps. Thus, the batch mixing step of Figure 1 may be combined with a batch settling step after dehydration of the mixture and subsequent rehydration thereof. It is, in fact, possible to carry on the mixing, dehydration, rehydration and settling steps all in the same kettle, which can be closed from the atmosphere and arranged to have a vacuum produced or continuous centrifugal separation can be performed after batch mixing and dehydrating steps. Thus the oil and neutralizing agent may be mixed in a kettle until neutralization is substantially complete. A vacuum may even be produced in the kettle during such mixing in order to carry off any gases as soon as produced, although the vacuum may be applied v after neutralization is substantially complete along with continued heating and agitation until substantially all of the water and other vaporizable materials have been removed. The agitation during the dehydration step prevents the soap stock from stratifying either by settling or being carried to the top of the kettle by gases, so that a substantially uniform mixture is produced. By continuing the agitation at a rate just sufficient to prevent stratification, a stream of substantially uniform mixture of oil and soap stock can be continuously withdrawn andv subjected to dry separating operations such as filtering or separation in basket type centrifugals. Such a stream of substantially uniform dehydrated mixture can, however, be more advantageously separated by admixing a stream of rehydrating agent in flow therewith and continuously centrifugally separating a fiowable soap stock from the oil as disclosed in Figure 1. However, a rehydrating agent such as those disclosed hereinbefore may be added to the kettle in which dehydration is performed and the agent thoroughly mixed with the oil and soap stock mixture therein to form a substantially uniform rehydrated mixture. By then continuing theagitation at a rate just sufficient to maintain the mixture substantially uniform, a stream of rehydrated mixture can be delivered directly to a continuous centrifugal separator with or without the mixing of additional rehydrating agent in flow. Also, the rehydrated mixture may be separated in the kettle by stopping the agitation and allowing the soap stock to settle from the oil, after which either the oil or the soap stock can be removed from the kettle to produce a neutralized oil. Furthermore, such a batch settling step may be performed in combination with the continuous dehydration step of Figure 1 by delivering a stream of oil from the dehydrating chamber into a settling chamber in lieu of delivering it to the centrifugal separators 44. The dehydrated mixture of oil and soap stock can either be hydrated in flow, as disclosed in Figure l, or hydrated in the settling chamber after having been introduced thereinto.

If desired, the color reducing step may also be carried out as a batch operation by adding color reducing agent to a body of the oil in a kettle, thoroughly admixing the same by agitation and then allowing the color impurities to settle out of the oil, or the continuous mixing of the color reducing agent with the oil may be employed in combination with a batch settling step mixing step with the color reducing agent may be employed in conjunction with the continuous centrifugal separation of the color impurities. In either case, the mixing of the color reducing agent with the neutralized oil is preferably carried out at relatively low temperatures, as described above, and then the oil heated either in flow or in a kettle to the necessary separation temperature.

Similarly, the washing and drying step may be a batch operation in which the water and refined oil are mixed in a kettle and the water subsequently allowed to separate from the oil. Either the water or oil may be removed from the kettle and, in case the water is removed, vacuum drying of the oil may take place in the same kettle.

The batch operations referred to constitute an improvement over prior batch operations, as the dehydration of the oil and soap stock mixture produces a much cleaner separation of the oil from the soap stock, so that a better neutralized oil is produced and less oil is entrained in the soap stock. Furthermore, dehydration permits non-saponifying alkalies such as sodium carbonate to be employed in a batch operation while still obtaining an emcient separation of the oil from the soap stock and substantially complete neutralization. The vacuum treatment in such a batch operation prevents excessive foaming. The division of the neutralization and reduction of color into two separate steps in accordance with the present invention produces improved results, even where all these'operations are in batch, although operations in which these two steps are combined by continuously mixing an excess of a caustic alkali neutralizing agent with the oil in a fiow mixer or adding caustic alkali in flow prior to separation, when a non-saponifying alkali has been employed for neutralization, decreases refining losses over such batch operations. The continuous dehydrating and rehydrating, combined with continuous separation and continuous color reducing steps, however, markedly reduces refining losses even over prior continuous processes in which an excess of a saponifying alkali is used in the neutralization step. Even in such process where a non-saponifying alkali or equivalent amounts of saponifying alkali are used, the rehydration reduces refining loss due to entrainment of oil in the soap stock.

The present invention, particularly the process involving continuous dehydration and rehydration and continuous separation steps, is particularly valuable in the case of low free fatty acid oils. With such oils the refining losses are ordinarily excessively high with respect to the free fatty acid content, in many cases being 10 to 12 times the free fatty acid content. By employing the present invention, however, the refining losses have been in many cases reduced by more than one-half, even with such low free fatty acid oils. One of the most important advantages of the present invention, however, is its adaptability to oils of various types and quality. Most animal and vegetableoils contain relatively large quantities of gums which assist in causing the soap stock to separate from the oil so as to leave a clear oil but which also cause the soap stock to emulsify or otherwise entrain relatively large quantities of oil. Even with oils containing relatively large amounts of gums, entrainment of the oil in the soap stock is markedly reduced, in many cases being substantially completely eliminated.

By employing the process of the present in-- high 'free fatty acid oils;

, larly adaptable vention, the soap stock of degummed oil, from which the gums have been substantially completely removed without removing the free fatty acids, can be separated substantially completely from the oil. The invention is particularly useful with so-called slow break oils which require extended treatment with the neutralizing agent in prior processes, even when caustic alkalies are employed for refining, in order to prevent excessive entrainment of oil in the soap stock. The 1 dehydration and rehydration treatment of the present invention prevents such entrainment. Thus, the present process is adaptable to low or cold pressed or hot pressed oils; slow break oils; oils contain- 14 ing extremely small amounts of gums such as degummed oils or partially degummed oils; or oils naturally containing large amounts of gums which have not been removed therefrom. Not only is the soap of the soap stock itself modified, 2 but the gums are also apparently modified by the dehydration treatment so as to cause a more complete separation of the gums from the oil upon rehydration. Thus the present process is particuto so-called degumming 24 processes in which a gum precipitating agent such as water, salt solutions, weak alkaline solutions or weak acid solutions such as boric acid, is added to the oil in the first instance instead of an alkaline neutralizing a'gent. Such degumming 3! agents, for example the degumming agents and gum liquefying agents disclosed in my copendi-ng application Serial No. 248,355, filed December 29, 1938, may be added to the oil either in the continuous or batch mixing step, and the mixture 35 subsequently dehydrated. The invention also finds utility in acid refining wherein strong mineral acids such as sulfuric or hydrochloric acids are mixed with the oil in order to pre cipitate foots containing the gums above referred 40 to. The gums or'foots are separated while in dehydrated form or preferably after a rehydration step, so as to materially cut down the amount of oil entrained in the separated foots.

As a specific example of a refining operation 45 employing soda ash as a neutralizing agent, soda ash solutions as rehydrating and flushing agents and caustic soda as a color reducing agent, 60,100 lbs. of crude cottonseed oil having a free fatty acid content of 0.7 and a color of 35 Y.5.0 50

R. after being subjected to the ofiicial cup test was mixed under rapid agitation in a kettle with a slurry comprising lbs. NazCOa admixed with lbs. of-water. The temperature of mixing was 80 F. and rapid agitation was continued 55 until a thorough mixture was obtained. The agitation was then slowed until just sufllcient to prevent settling or stratification of the soap stock. A.stream of the mixture at a rate of approximately 6 gallons per minute was pumped through 00 mately 0.1%. A stream of the dehyrated mixture 70 was continuously pumped from the dehydrator through a flow mixing zone where a 20 B. NazCOa solution at F. was added.

The rehydrated mixture was then sent through another heating coil in which its temperature 7 The mixture was maintained under 65 rehydrating agent;

was raised .to. 195 F. and. delivered to three centrifugals of the heated type above referred to operating in parallel along with a stream of additional rehydrating solution of B. NMCO: added just before the mixture entered the separators.

By the employment of the term oils in the claims I intend to embrace glyceride fats and oils, irrespective of the viscosity thereof.

By the employment of the terms rehydrating' hydrating agent"; hydrating medium. as employed in my claims, I intend to define and embrace the hydration of the foots or 'soap stoc as contra-distinguished from a process, such as exhibited in Brucke Patent 2,035,589 wherein alcohol is used in such quantities during separation as to substantially'completelydissolve the soap component of the soap stock.

What I claim is: t

1. The process of refining glyceride oils and fats, which comprises, mixing an aqueous refining reagent with said oils to form a mixture of oil and foots containing water, subjecting said mixture to a dehydration treatment to remove the major portion of said water, and thereafter rehydrating said mixture and separating said foots from said oil.

2. The process of refining glyceride oils and fats containing free fatty acids, which comprises, mixing an alkaline neutralizing agent with said oil to neutralize "said free fatty acids in the presence of moisture to form a mixture of oil and soap stock, subjecting said mixture to a vacuum treatment to remove a substantial portion of said moisture, and thereafter adding to said mixture a rehydrating agent to condition the soap stock for separation and separating the thus conditioned soap stock from said oil.

3.-The process of refining glyceride oils and fats containing free fatty .acids, which comprises, mixing a non-saponifying alkali in admixture with water with said oil to form a mixture of oil and soap stock containing water continuously advancing a stream of said mixture to a dehydration zone, dehydrating saidmixture in said zone to remove a substantial amount of the water contained in said soap stock, and there after rehydrating said mixture and separating said soap stock from said oil.

4. The process of refining glyceride oils and fats containing free fatty acids, which cornprises, admixing sodium carbonate with said oil in an amount suflicient to neutralize said free fatty acids-in the presence of moisture and form soap stock, advancing a stream of the resulting mixture to a dehydrating zone, heating said stream during continuous fiow thereof, subjecting the mixture of oil and soap stock to a dehydration treatment in said zone in order to remove a substantial amount of said moisture, and thereafter adding a hydrating agent to said mixture and separating the soap stock from said oil.

5. The process of refining glyceride oils and fats, which comprises, mixing a refining reagent with said oils, reacting said reagent with said oil in the presence of moisture to form a mixture of oils and foots, dehydrating said mixture to remove a substantial portion of said moisture, gaseous and volatile materials therefrom, there after rehydrating said mixture to condition the sameifor continuous centrifugal separation, and continuously centrifugally separating the foots from the rehydrated mixture.

6. The process of refining glyceride oils and fats containing free fatty acids, which comprises, mixing an aqueous solution of a neutralizing agent for said free fatty acids with said oil in an amount sufilcient to neutralize said free fatty acids and form soap stock, continuously pumping a stream of the resulting mixture of oil and soap stock into a dehydration zone, subjecting said mixture in said zone to suflicient temperaturt and reduced pressure conditions to remove a sub- 10 stantial portion of the water and vaporizable materials, continuously pumping a stream of the dehydrated mixture from said zone, continuously mixing a stream of rehydrating agent with said stream of mixture continuous centrifugal separation, and continuously centrifugally separating said soap stock from said oil. a

'7. The process" of refining glyceride oils and to condition the same for is fats containingv free fatty acids and color im- 20 purities, which comprises, admixing an aqueous solution of an alkaline neutralizing reagent with said on in an amount .substantially equivalent to said free fatty acids to form soap stock, continuously pumping a stream of the resulting mixture of oil and soap stock into a dehydrating zone, subjecting said mixture in said zone to sufficient temperature andireduced pressui e conditions to substantially dehydrate said xture, continuously pumping a stream of t drated mixture from said zone, contin 'iisly mixing a stream of rehydrating agent with said stream of mixture to condition the same for continuous centrifugal separation, continuously centrifugally separating said soap stock from said 85 oil, admixing a stream of color reducing agent comprising a caustic alkali with a stream of the separated oil, and thereafter continuously centrifugally separating color impurities from said oil.

8. The process of refining glyceride oils and fats containing free fatty acids and color impurities, which comprises, mixing an aqueous so lutionof a non-saponifying alkali with said oil in an amount sufficient to neutralize said free fatty acids and form soap stock, continuously pumping a stream of the resulting mixture of oil and soap stock into a dehydrating zone, subjecting said mixture in said zone to sufllcient temperature and reduced pressure conditions to substantially dehydrate s'aid mixture, continuously pumping a stream of the dehydrated mixture from said zone, continuously mixing a stream of rehydrating agent with said stream of mixture to condition the same for continuous centrifugal separation, continuously centrifugally separating said soap stock from said oil, admixing a stream of color reducing agent comprising a caustic alkali with a stream of the separated oil, and thereafter continuously centrifugally separating color impurities from said oil.

fats which comprises: mixing an aqueous refining reagent with said oils to precipitate impurities therein to form a mixture of oil and foots, removing vaporizable and gaseous materials including a substantial portion of the water from said mixture, thereafter adding a hydrating agent to said mixture and separating said foots from said oil.

10. The process of refining glyceride oils and fats which comprises: neutralizing said oil in the presence of moisture to form a mixture of oil and soap stock, removing gaseous and vapor- 9. The process of refining glyceride oils and izable impurities including a substantial portion of said moisture from said mixture, adding a hydrating agent to said mixture, separating the soapg stockfrom said 011 under elevated temperatures, continuously reducing the temperature of the oil and while at such reduced temperature reducing the color thereof.

11. The process as defined in claim 10 in which the color. is reduced by the addition of a small amount "of caustic alkali and thereafter removing the color impurities by centrifugation.

12. The process of refining glyceride oils and fats containing free fatty acids which comprises: mixing a non-saponifying alkali with said oil, neutralizing said free fatty acids in the presence of moisture to form soap stock, removing gaseous and vaporizable materials including a substantial portion of said moisture therefrom, thus producing a mixture incapable of desirable centrifugal separation, continuously conditioning said mixture of oil. and soap stock for centrifugal separation by adding thereto a hydrating medium and continuously centrifugally separating the thus conditioned soap stock from the oil.

13. The process as defined in claim 12 in which the mixture is further conditioned for centrifugal separation by the employment of a temperature, while undergoing separation, in excess of 160 F. whereby the soap stock is softened.

14. A continuous process for refining glyceride oils and fats containing free fatty acids and color impurities which comprises the steps of: admixing in stream flow andwhile excluding air a quantity of soda ash in an amount at least sufiicient to substantially neutralize the free fatty acids in the presence of moisture and to form soap stock, advancing the mixture to a vapor separating chamber, closed from the atmosphere, and there removing liberated carbon dioxide and vaporizable materials including a substantial portion of said moisture therefrom, while maintaining an elevated temperature and vacuum in said vapor separating chamber thereby forming a mixture of oil and soap stock which is incapable of satisfactory centrifugal separation, conditioning the mixture for centrifugal separation by the addition thereto of a hydrating medium and promptly centrifugally separating the thus conditioned soap stock from the refined oil.

15. The process as defined in claim 14 in which the centrifugal separation is aided by the employment of heat not substantially below 195 F.

16. The process as defined in claim 14 in which the stream of oil thus separated is continuously cooled to reduce its temperature and caustic alkali is added thereto to precipitate the color impurities and the mixture subjected to further centrifugation to separate the precipitated color impurities from the refined oil.

17. A process for refining glyceride oils and fats containing free fatty acids and color impurities which comprises the steps of: admixing with said oils soda ash in an amount sufflcient to substantially neutralize the free fatty acids, in the presence of moisture, and to perceptibly reduce the color of said oil, removing impurities including a substantial portion of said moisture from said mixture by subjecting it to an elevated temperature thus producing a mixture in which the soapstock and oil is incapable of satisfactory gravity separation, conditioning the soap stock for gravity separation by the addition thereto of a hydrating medium and separating the thus conditioned soap stock from the refined oil.

7 18. In the process of refining glyceride oils and fats in which impurities in said glyceride are precipitated as foots and separated from said oil by difference in specific gravity, the improvement which comprises: forming a dehydrated mixture of said oil and roots continuously" admixing a stream of said dehydrated mixture with a stream of a hydrating medium to condition the said foots for the act oi. centrifugal separation and thereafter continuously centrii'ugally sep'arating said conditioned foots from said oil.

' 19. The process as defined in claim 18 in which an aqueous solution of an alkali is employed to rehydrate the mixture.

20. The process as defined in claim 18 in which an aqueous solution of sodium carbonate is employed to rehydrate the mixture.

21. The process as defined in claim 18 in which an aqueous solution of sodium sulfate is employed to rehydrate the mixture. 22. A process for the refining of glyceride oils and fats comprising the steps of: first admixing the oils with an alkaline refining reagent and eifecting substantial neutralization of the free fatty acids in the presence of moisture, thereafter, following said neutralization, subjecting the mixture to a dehydration treatment to remove substantially all of the said moisture and to produce a mixture comprising dehydrated foots and oil, conditioning the dehydrated foots for separation by the difference in specific gravity between the oil and foots by adding to the mixture an aqueous rehydrating agent.

23. The process of refining glyceride oils-and fats containing free fatty acids which comprises: admixing said oil with sodium carbonate, advancing a stream of said mixture containing moisture to a dehydrating zone, heating said stream during flow thereof and delivering the same into said zone, subjecting the material in said zone to vacuum treatment at an elevated temperature to remove a substantial portion of said moisture, continuously withdrawing a stream of the treated mixture, continuously admixing a stream of a hydrating medium with said treated mixture to condition the same for continuous centrifugal separation and continuously centrifugally separating the thus conditioned soap stock from said oil.

24. A high speed continuous process of refining glyceride oils and fats containing free fatty acids which comprises: mixing the oil with an aqueous solution of an alkaline reagent, advancing the mixture, as a stream, under pump pressure to a dehydrating zone and there continuously removing vaporizable impurities and water from said mixture under vacuum conditions, continuously withdrawing a stream of the thus dehydrated mixture, continuously and quickly conditioning the mixture for centrifugal separation of the soap stock from the oil by the introduction of a stream of hydrating medium and continuously centrifugally separating the thus conditioned soap stock from the oil.

25. The process as defined in claim 24 in which the amount of the alkaline reagent added during the process is at least several times that theoretically required to neutralize the free fatty acids.

. 26. The process as defined in claim 24 in which the aqueous medium comprises a solution of alkali metal carbonate.

27. A continuous process for the refining oi glyceride oils and fats containing free fatty acids which comprises the steps of: mixing an alkalinerefining reagent with said oils and effecting neutralization in the presence of moisture, continuously subjecting v the mixture to dehydration treatment to remove the major portion of said moisture and thus produce a dehydrated mixture incapable of satisfactory centrifugal separation, conditioning the mixture for such centrifugal separation by adding thereto a hydrating medium and continuously centrifuge-11y separating the thus conditioned soap stock from the refined oil. 28. The process as defined in claim 27 in which the amount of alkaline reagent added during the process is atleast several times that theoretically required to neutralize the free fatty acids.

BENJAMIN CLAYTON.

CERTIFICATE 0 CORRECTION.

Patent No. 2,190,59 February 1 19m.

BENJAMIN CLAYTON. It is hereby certified that error appears; in the printed specification of the above numbered patep t requiring correc tion as follows: Page 2, second columhfline 25-26, for "hehydration"- read rehydration; line 58, 0 "eeffct read effect; page 5, first column, line 19, for "1929" read 1959; page 1;, first column, line 61, for "611 95" read 661195; page 5, first column, line l6,"for "h ydzbcarbins" read hydrecarbons; and seeond column, line 25, far "or" read 01; page 6, secdnd cblumn, 1111671,- for "difficult y" read difficultly; and that the said Letters Patentshould be read with this cor rection therein that the seine may cbnform to the record of the case in the Patent ornce'.

Signed and sealed this .2ndlday or April, A. D. 191p.

Henry Vgn Arsdale, "Acting Commissioner of Patente. 

